This program resource continues to supply sufficient numbers of animals of satisfactory health status to support the bioassay needs. In addition, effort is expended to develop new animal models and/or documentation that will enhance their use in the intramural and extramural program areas. Species and strains of animals that are not otherwise available in adequate supply are provided through a variety of mechanisms, i.e., Frederick Cancer Research Center and contracts of the Division of Cancer Treatment. The husbandry aspects of the bioassay extramural contracts have received a great deal of attention and have been significantly upgraded. In conjunction with the appropriate prime contractor staff members, variables impacting upon the proper execution of the protocols are identified and methodically eliminated in a manner that will not disrupt the ongoing program.